Modern data processing systems, such as a Macintosh computer running the Macintosh operating system, or a mobile computing device, such as an iPhone running the mobile operating system iOS, can launch an application by activating a file that is usable with the application. The file is in a file system maintained by the data processing system or mobile computing device, and may be a document or other type of data or content, such as a word processing document, spreadsheet, PDF file or media file, etc.
Sometimes, however, the operating system is not able to launch an application because the operating system cannot determine which application to use. For example, the file may be of a type that is unknown to the operating system because there is no application currently installed on the system or device with which the file may be used.